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Revision of the Aspicilia reptans group, a major lichen component of soil biocrusts in western North America

Citation

McCune, Bruce; Di Meglio, Joseph (2022), Revision of the Aspicilia reptans group, a major lichen component of soil biocrusts in western North America, Dryad, Dataset, https://doi.org/10.5061/dryad.tmpg4f4zs

Abstract

Aspicilia in the broad sense is one of the most common and speciose genera of saxicolous lichens in the World. It is also a common genus in the biological soil crusts of arid and semi-arid parts of North America, as well as on other continents. Analysis of DNA sequences and morphology from Aspicilia in soil crusts revealed previously unrecognized species that are ecologically, geographically, morphologically, and genetically distinct. We describe six previously unrecognized species (Aspicilia albonota, A. diploschistiformis, A. papilliformis, A. spicata, A. subcontinua, and A. wyomingensis), supported by phylogenetic reconstruction from ITS and nuLSU sequence data. The combined ITS+LSU tree with 368 specimens (339 ITS, 145 LSU, including 177 new sequences) places these species in various genera that have been segregated from Aspicilia, but because of problems in generic delimitation, we adopted a broad genus concept and assigned all of the new species to Aspicilia for simplicity and practicality. Previous segregates from Aspicilia (Agrestia, Aspiciliella, Aspilidea, Chlorangium, Circinaria, Lobothallia, Oxneriaria, Sagedia, Sphaerothallia, and Teuvoa) were in some cases nested within each other, lacking statistical support, or polyphyletic. Recognition of these genera would require erection of at least three new small genera to accommodate the sequenced species of Aspicilia s.l. that fall outside of those clades. The new species are mostly infertile, primarily terricolous, and are separable in most cases by a key to subtle differences in morphology, anatomy, and secondary chemistry. Nevertheless, the plastic, substrate-coating morphology and common sterility present serious challenges to purely microscopic identification. In addition to recognizing these new species, we describe a new variety, A. californica var. gigantea from Oregon, allopatric with the typical variety, and having thalli about twice the size of typical A. californica. We hypothesize that the new variety has a polyploid origin. We synonymize A. mansourii described from Iran under A. reptans s. str., based on morphology, chemistry, and ITS sequences. Aspicilia reptans s. str. is thus new to Eurasia. The other new taxa are so far known only from western North America, with the exception of A. wyomingensis, which occurs in Spain, based on phylogenetic placement of a specimen with an ITS sequence. The Eurasian species A. aspera is tentatively confirmed for North America. Two additional new species are described, A. maritima and A. supralittorea, both from the Pacific coast of Oregon.

Methods

FASTA file for concatenated ITS and nuLSU (partial) alignments; voucher specimens, Sanger sequencing, phylogenetic analysis.